Recently, attention has been given to organic EL (electroluminescence) devices, as devices for use as next-generation light emitting displays with low consumption power. An organic EL device is basically composed of a substrate, and an organic EL element having an organic EL layer and a pair of electrode layers provided over the substrate. The organic EL layer is composed of at least one layer including a light emitting layer formed of an organic light emitting material. Such an organic EL device emits multicolor light derived from the organic light emitting material. Further, the organic EL device is a self-luminous device. Therefore, attention has been focused thereon for use as a display such as television (TV).
The organic EL device is, more specifically, configured to be formed by stacking an anode layer, an organic EL layer, and a cathode layer in this order over the substrate as constituent layers of an organic EL element.
In methods for manufacturing such an organic EL device, vacuum deposition and coating are commonly known as a technique for forming constituent layers of the organic EL element (which may be hereinafter referred to simply as constituent layers) over the substrate. Among these, vacuum deposition is mainly used, particularly because of the capability of increasing the purity of the materials for forming constituent layers and the ease of achieving long life span.
In the above-mentioned vacuum deposition, each constituent layer is formed by performing deposition using an evaporation source provided in a vacuum chamber at a position facing the substrate. Specifically, a material for forming the constituent layer is heated by a heating unit provided in the evaporation source so as to be vaporized. The vaporized material for forming the constituent layer (vaporized material) is discharged from the evaporation source. The vaporized material is deposited over the substrate as a constituent layer, thereby forming the constituent layer.
In such vacuum deposition, a roll process is employed from the viewpoint of cost reduction. The roll process is a process in which: a substrate in the form of a strip wound into a roll is continuously unwound; constituent layers are continuously deposited over the substrate while the unwound substrate is being moved; and the substrate over which the constituent layers have been deposited is wound up into a roll (see Patent Literature 1).